Dr. Edmond Locard (1877–1966) In early 20th century, he formulated the basic principle that “every contact leaves a trace.”

Locard’s Principle Principle of Exchange Part 1: when a person comes into contact with an object or another person, a cross transfer of physical evidence can occur

Locard’s Principle Part 2: the intensity, duration and type of weapon determine the extent of transfer

Types of Evidence Circumstantial: indirect evidence Direct - NOT witnessed - may link a suspect and a crime scene ex. Suspect’s gun found at crime scene Circumstantial: indirect evidence Direct firsthand observations: - eyewitness accounts dashboard video cameras confessions

What will evidence collected at a scene do for the investigation? Types of Evidence Testimonial evidence includes oral or written statements given to police as well as court testimony by people who witnessed an event. (Physical-weapon, bullets, clothing) (Biological- from living, blood, grass) Trace evidence refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells. What will evidence collected at a scene do for the investigation? May prove that a crime has been committed Establish key elements of a crime Link a suspect with a crime scene or a victim Establish the identity of a victim or suspect Corroborate verbal witness testimony Exonerate the innocent. Give detectives leads to work with in the case Source: http://www3.sc.maricopa.edu/ajs/crime_scene_technician.htm

Trace evidence: TINY Pet hair on clothes or rugs Hair on brush Fingerprints on glass Soil tracked inside on shoes Drop of blood on t shirt A used facial tissue Paint chips Broken glass Fiber from clothing

Individual evidence: single person -DNA, fingerprint Class evidence: narrows the identity to a group ex. Blood type ABO, color of… Shoe size

Class Discussion Casey Anthony – new use of Air Sample Coverage of Casey Anthony Murder Trial OJ Simpson – “If the glove doesn’t fit, then you must acquit” OJ Simpson Trial Criminal Evidence Suggested STOP of Day 1

End Part 1

CSI Team: Police Officers: usually first responder Crime Scene Investigators: document crime and collect physical evidence Recorder Sketch artist Photographers Evidence collectors Medical Examiners: coroners may be necessary to determine cause of death in a homicide case Detectives: look for leads, interview witnesses and talking to the CSI about evidence Specialists: entomologists, psychologists,anthropologist, toxicologist, ballistics,

Securing and Collecting the Evidence Must be properly packaged, sealed and labeled Specific procedures must be followed for collection and storage Liquids and arson remains: airtight, unbreakable container Biological evidence: breathable containers to reduce mold

Securing and Collecting the Evidence After evidence is allowed to dry, it is then packaged into a paper bindle Paper bindle (druggist fold) then placed in paper or plastic container Outer container then sealed with tape and signed by the collector on the label

Evidence log and Chain of Custody document is attached to the evidence container. Contains: Case number Item inventory number Description of the evidence Date and Time of recovery Signature of person recovering evidence Signature of any witnesses present during collection Optional for reference evidence (evidence collected from a known person): Name of suspect Name of victim

Chain of Custody Form Example

CHAIN OF CUSTODY: Must be maintained to secure evidence Collector finds evidence and bags it in appropriate container The final container is the collection bag labeled with pertinent information Collection bag is sealed and collector’s signature written across sealed edge of the container Then the evidence is taken to evidence storage and logged Not all evidence collected gets tested. Once the necessary tests are determined, then the evidence is checked out and sent to a lab

CHAIN OF CUSTODY: Must be maintained to secure evidence After evidence has been received by the Laboratory: Tech opens bag (tears) somewhere that isn’t over someone else’s evidence seal Technician handles evidence then repackages evidence in original packaging and then seals in new packaging Sign chain of custody log Ensures responsible handling from crime scene to courtroom and vice versa

Analyze Evidence FBI crime is largest forensics lab in the world. They: Process all evidence to determine facts of the case Each technician has one specialty (one type of evidence). See next slide. Lab results sent to lead detective Test results lead to crime scene reconstruction Detective takes evidence and tries fit into scenario Analysis can link a suspect to scene or victim or lead to acquittal Direct evidence is more compelling than circumstantial

Investigating the Evidence Forensic Science disciplines at the Illinois State Police Crime Labs Drug Chemistry – Determines the presence of controlled substances and the identification of marijuana Trace Chemistry - Identification and comparison of materials from fires, explosions, paints, and glass. Microscopy – Microscopic identification and comparison of evidence, such as hairs, fibers, woods, soils, building materials, insulation and other materials. Biology/DNA – Analysis of body fluids and dried stains such as blood, semen, and saliva. Toxicology – Tests body fluids and tissues to determine the presence of drugs and poisons. Latent Prints - Identification and comparison of fingerprints or other hidden impressions from sources like feet, shoes, ears, lips or the tread on vehicle tires. Ballistics (Firearms) – Study of bullets and ammunition through the comparison of fired bullets, cartridges, guns, and gunpowder patterns on people and objects. Toolmarks – Examines marks left by tools on objects at a crime scene or on a victim, such as a hammer used to break a door or a screwdriver used to pick a lock. Questioned Documents - Examination of documents to compare handwriting, ink, paper, writing instruments, printers, and other characteristics that would help to identify its origin. Suggested STOP of Day 2 Source: http://www.isp.state.il.us/forensics/

National databases available to Forensic Scientists List of Forensic Databases from NIJ Journal No. 258, October 2007 On your own sheet of paper, create a table listing the different databases available and a brief description of each

Crime Scene Reconstruction Hypothetical sequence of events Examine evidence and compare to witness accounts to determine reliability Evidence does not lie but it can be staged

Staged Crime Scenes Unique problem: evidence does not match testimony Common situations: Arson: stage fire to cover rubbery, murder Suicide/murder: death may be alcohol or overdose Burglary: staged to collect money

Things to consider when determining if staging occurred: Initially treat all death investigations as homicide, however: Do the type(s) of wounds found on the victim match the weapon employed? Could the wounds be easily self inflicted? Establish a profile of the victim through interviews with friends and family Evaluate the behavior ( mood and actions) of the victim before the event Evaluate the behavior ( mood and actions) of any suspects before the event Corroborate statements with evidential facts Reconstruct the event Conduct all forensic examinations to determine the facts of the case

SUMMARY Locard’s principle Evidence may be direct: eyewitness or Circumstantial: does not directly prove a fact Evidence can be physical or biological (trace can be either) CSI team: police officers, detectives, CSI investigators, medical examiners and specialists CS investigation: recognizing, documenting and collecting evidence from a scene First responding officer: id extent of crime scene (including 1 and 2), secure the scene and segregate witnesses walk the scene, id evidence then document scene by photos and sketches Evidence must be properly handled, collected and labeled to maintain Chain of Custody Evidence is analyzed in a forensic lab, results provided to detectives who fit results into crime scenario

What evidence would you collect? Mock Crime Scene: http://www.masss.gov Mock Crime Scene: http://www.masss.gov